Stellar mass maps of NGC 3115 in six age bins, as in Fig. 7. These maps show the present day stellar mass distribution as a function of its mass-weighted age. For each panel, the total stellar mass per age bin (in solar mass) is indicated in the bottom right corner and the colour scheme limits (corresponding to the colour bar at the top) are in the bottom left corner, and differ from each another. The noticeable change in the shape of the iso-mass contours between 10−12 Gyr and 12−14 Gyr, from rather flat to more spheroidal, suggests a more dissipative mass assembly at early epoch (age > 12 Gyr) possibly from a major merger. Panels a) to c) suggest that extended star formation occurred in situ in the disc component of NGC 3115.